1. Field of the Invention
The present invention relates to the field of data transmission apparatus, methods, and systems. More specifically, it relates to the field of laterally translatable downhole data transmission apparatus.
2. Description of the Related Art
Downhole drilling and production well operations usually have an objective of locating and extracting useful fluids and/or gases such as hydrocarbons or water from underground formations.
Many attempts in the art have been made to optimize the drilling process by enabling the transmission of data along the tool string. Several problems arise in this endeavor. For example, a tool string generally comprises a plurality of tool string components that are attached to each other through joints of mated threads. As tool string components are often being added to and taken away from the tool string, it is generally impractical to transmit data through the tool string using a continuous wireline approach. Furthermore, drilling mud and other fluids are generally circulated through the tool string. These fluids, whether electrically conductive or electrically insulating, may impede, inhibit, or short out electrical signals—especially when they are exposed to electrical contacts.
One approach to downhole data transmission that attempts to overcome the aforementioned complications involves the use of inductive couplers to transmit electrical signals between tool joints in a tool string. The inductive coupler system described in U.S. Pat. No. 6,670,880 by Hall, et al., and herein incorporated by reference for all it discloses, has been particularly successful in overcoming several of the challenges associated with transmitting data signals through a tool string.
In some tools, such as downhole motors, jars, and shock absorbers, it may become necessary to transmit an electrical signal through components that move relative to each other. Some attempts to solve this problem are known in the art. For example, U.S. Pat. No. 6,540,032, to Krueger, discloses an apparatus for power and data transfer over a gap between rotating and non-rotating members of downhole oilfield tools by means of an inductive coupling. An electronic control circuit associated with the rotating member controls the transfer of power and data from the rotating member to the non-rotating member.
U.S. patent Ser. No. 10/653,604 filed on 2 Sep. 2003 to Hall, et al. discloses using a coiled coaxial cable for transmission of data through a mandrel that translates axially with respect to a housing. The coiled coaxial cable acts as a mechanical spring.